Many current strip processing lines used in the processing of continuous metal strips, such as in pickling processes for example, use long horizontal loops in a so called horizontal loop system as a means of temporarily storing the strip, so that the processing section of the line may run continuously, while the entry and/or delivery sections of the line are stopped to permit, for example, welding attachment of a trailing strip edge to a leading succeeding strip edge, in a usual manner, in continuous strip processing.
The means of storing strip or accumulating strip, is normally accomplished in a system by means including looper cars on which are mounted looper rolls. The strip is passed around the looper rolls and the looper cars are traversed back and forth along tracks so that the strip is stored and accumulated in loops consisting of upper and lower strand runs. The strip can be stored and accumulated, or fed back into the processing line, depending upon the direction of movement of the looper cars. In such a system or process, it is necessary, however, that the top strand of the loops thus formed be supported from sagging down and engaging the bottom strands. The systems can include a plurality of looper cars, with looper rolls, at opposite ends of the processing line, such as entry and delivery ends, depending upon the amount of strip it is necessary or desirable to store for a specific process installation involved.
Current apparatus and practices utilize various types of supports, including support rollers positioned at intervals under the top loop strand, or between the top and bottom strands. Such supports, however, must be removed from the path of a looper car as the loop is shortened, during refeed of strip, and must be reinserted at intervals after passage of the looper car as the loop lengthens. Such a system requires some means of signaling the position of the car relative to the position of the support device so as to initiate its movement at the proper time, and additionally requires application of a motive force to the support to move and accelerate, and decelerate, the mass of the support device as it moves into or out of the path of the rapidly moving looper car.
Some currently known and used signaling and support roller moving means, including electrical and mechanical devices, as also air and hydraulic devices, for moving the rollers, all have a common drawback in that failures can occur, and heretofore such known support devices have for the most part included a common characteristic of being in the path of the looper car when supporting the strip. Any failure of the electrical, air, hydraulic or mechanical signaling means, or the means for applying the motive force to move the supports, therefore usually results in a collision of the support device with the looper car, or with the strip or both, with possible substantial damage to one or more of the components. In turn, this damage results in costly repairs and maintenance, and, of substantial importance and significance, to costly loss of production due to line stoppage to clear wreckage and perform needed repairs.
Some known apparatus and systems additionally frequently involve many moving parts which require so called operational down periods for the purpose of lubrication, maintenance, and eventual replacement due to wear.
Typical prior art strip looping systems, such as used in strip processing lines of the type with which the present invention is concerned, are disclosed for example in U.S. Pat. No. 3,515,327, issued June 2, 1970 to H. J. Bortmus; U.S. Pat. No. 2,830,809, issued Apr. 15, 1958 to P. Morocco et al; and U.S. Pat. No. 2,750,187, issued June 12, 1956 to B. Bannister et al.
The Bortmus and Morocco patents utilize strip supports positioned below the upper strand run of the loop, and these support means must be moved out of the path of the traversing looper car. In Bortmus the support rollers pivot out of the path of a looping roll during looping roll movement resulting from a decrease in loop size as the material is fed into the processing run for processing continuity. In Morocco the supporting rolls are positioned beneath the strip in the upper run, with the plurality of strip-supporting rollers having adjacent runs thereof interconnected by a pair of chains, with the rollers in the line being collapsible and expandible with respect to each other to prevent damaging contact between stationary and movable rolls.
The Bannister patent discloses a looper system wherein an upper run of the loop is suspended or supported by magnetic conveyor rollers, with the lower or return run being carried on ordinary rollers or skids. The magnetic rollers are positioned or supported by means of brackets extending as cantilevers, and the magnetic rollers are designed to exert sufficient magnetic attraction to suspend the upper run of the loop of steel strip through supporting contact with the top or upper surface of the strip material. In this system, however, the fed or moving strip comes into tangential contact with the magnetic rollers progressively at their lowest points. While the strip of steel is supported from above in this patent, in a horizontal loop, by magnetic rolls, it is to be noted that when these magnetic rolls are used, the magnetic field is rather limited in area, and only a single line contact is made with the strip. In use, the apparatus of Bannister has certain drawbacks. A more elaborate discussion of the differences and drawbacks appears hereinafter following a detailed presentation of the present invention.
Another existing looper system is shown in U.S. Pat. No. 3,687,348, issued Aug. 29, 1972 to William R. Scheib. This patent is typical of the known patent art dealing with conventional looper car structures and systems with which used. This patent also involves the use of movable strip support rollers.
Also known in the art are metal sheet magnetic conveyor systems or apparatus such as shown for example in U.S. Pat. No. 3,606,313, issued Sept. 20, 1971 to D. Buccicone. This same inventor additionally has been the recipient of several other U.S. patents all relating to similar overhead magnetic conveyor units. While overhead magnetic conveyor units are well known in the patent art, as exemplified by the Buccicone patent, these patents do not teach or suggest the combination with a looper car in a strip processing line of the magnetic support concept in the manner of the present invention.